| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To facilitate pin hole alignment upon connecting a main boom to a front boom with a single pin to allow both booms to rotate relative to each other and ensure the folding cranking action of the connected booms. <P>SOLUTION: The front end of an upward rotating main boom 8 is provide with a boss 18 extending in the direction of width of the boom 8, and the base end of a downward rotating front boom 10 is provided with a downward opening hook 19. Scooping operation is carried out as the boss 18 and the hook 19 are engaged with each other to match a pin hole 15 of the front boom 10 to a pin hole 16 of the main boom 8. The boss 18 and the hook 19 are arranged to satisfy the condition that the hook 19 and the boss 18 separate from each other when an angle made between both booms 8 and 10 becomes a maximum angle at working time and that the distance of separation increase as the angle between the booms 8 and 10 decrease from the maximum angle. <P>COPYRIGHT: (C)2010,JPO&INPIT</p> |
